Did my 16-miler yesterday, 3:11:50. The last 2 miles were pretty torturous, but I got it done. Felt a little adductor pain in the first few miles, but kept going and it disappeared by about mile 5 or so. Slow as molasses, I know, but I'm competing w/ myself, no one else.
Somehow, I think a sub-5:00 marathon is a little out of reach this year. I've been doing my long runs between 11:15 and 11:30 miles up until yesterday, when I had to drop it to just under 12:00 miles. A 5 hour marathon would be 11:27 miles, and right now, I don't see being able to keep that up for 26 miles. Not being defeatist, but trying to be realistic.